1. Field of the Invention
This invention relates to novel phosphate esters prepared from polycyclic phosphorohalidites. These esters, which are useful as flame retardants especially for rigid polyurethane foams, have the formula: RO--(A).sub.m (B).sub.n ]H wherein A has the structural formula ##SPC3##
And B has the structural formula ##SPC4##
Wherein R, R.sup.1, and R.sub.2 are the same or different and are alkyl radicals, and m and n are integers from 0 to about 4, the sum of m plus n being from one to about four. It is understood that structures A and B are randomly distributed within these oligomeric compounds.
2. Description of the Prior Art
Bliznyuk et al., Zh. Obshch. Khim, 34, p. 1169-70 (1960), teach reacting PCl.sub.3 with an excess of alcohol in the presence of chlorine to produce PO(OR).sub.3. Frank et al. J. Org. Chem., 31, p. 872- 5 (1966), converted simple trialkyl phosphites (RO).sub.3 P to the corresponding phosphates (RO).sub.3 PO in a similar fashion.
Neither of the above references however disclose the conversion of polycyclic phosphorohalidites to the phosphate esters of this invention.